In a conventional headlight control device (for example, JP 2004-98819A), the illumination in front of a vehicle is detected by an illumination sensor or the like. The headlight is automatically switched over to the high-beam when the illumination in front is darker than a predetermined threshold illumination level. It is switched over to the low-beam when the illumination in front is brighter than the threshold illumination level to maintain visibility while preventing dazzling to vehicles in front.
The operation for switching over to the low-beam and to the high-beam is executed relying upon a change in the illumination in front, and the switching operation is often executed too frequently depending upon the conditions in front. This frequent switching often becomes offensive to drivers of other vehicles.